Multi-rotor helicopter and rotor arrangement for multi-rotor helicopter

Abstract

The invention relates to a multi-rotor helicopter having a plurality of rotor devices (14) which have at least one rotor blade (20) which is rotatable about a rotor blade axis (22). According to the invention, the rotor device (14) further comprises: a first section (24), which is rotatably driven about an axis of rotation (16); a second section (26), which can be moved relative to the first section (24) about an axis running parallel to the rotational axis (16) and to which the rotor blade (20) is fastened or which has the rotor blade (20), the relative position of the second section (26) relative to the first section (24) being dependent on a torque (M), driving the first section (24) with the torque; and a mechanical coupling (34) which couples the relative position of the first section (24) with respect to the second section (26) to the rotational position of the rotor blade (20) about the rotor blade shaft (22).

Description

Technical Field

[0001] The invention relates to a multi-rotor helicopter and a rotor device for a multi-rotor helicopter according to the preambles of the independent claims. Background Art

[0002] A drone in the form of a multi-rotor helicopter is known from the market, usually including four rotor devices. Each rotor device has a rotor shaft driven by an electric motor, a rotor head coupled to the rotor shaft and at least two rotor blades fastened on the rotor head. The known multi-rotor helicopter is usually controlled by the speed change of the rotor device, because this can be achieved with fewer movable parts. In such a case, the propeller can be rigid and only requires certain electronic devices for engine control. Wu,Xionan,2018,Design and Development of variable Pitch Quadcopter forlong Endurance Flight,Master Thesis,Oklahoma State University The use of actuators is described in a multi-rotor helicopter for actively controlling the position of the rotor blades around the rotor blade shaft, that is, controlling the angle of attack of the rotor blades. In addition, variable pitch propellers are known, for example, from EP 0 589 338 A1 and US 1,864,045 A. Summary of the invention

[0003] The object of the present invention is to provide a multi-rotor helicopter which generates little noise during operation, can be dynamically controlled and is simple to manufacture and is very efficient.

[0004] This object is achieved by a multi-rotor helicopter and a rotor device for a multi-rotor helicopter having the features of the independent claims. Advantageous further developments are indicated in the dependent claims.

[0005] The present invention solves the above-mentioned problem by a mechanical automatic device, which is used to couple the drive torque with the blade angle of attack in the rotor device of a multi-rotor helicopter, that is, the blade angle adjustment or the rotational position or angle of attack of the rotor blade around the rotor blade axis, which is realized without an active actuator and acts automatically and only based on the torque or torque change present on the rotor shaft. This allows the multi-rotor helicopter according to the present invention to be equipped with a rotor device, which has a relatively large diameter and therefore a relatively large rotor circular surface. The power required to generate a certain thrust is thereby reduced, that is, the efficiency of the rotor device is improved. Therefore, due to the present invention, a longer flight time can be achieved with the same battery capacity. In addition, the noise emission is reduced with the larger diameter of the rotor device and the smaller rotation speed associated therewith. That is, the multi-rotor helicopter according to the present invention is particularly quiet.

[0006] Specifically, the advantages are achieved by a multi-rotor helicopter with a plurality of rotor devices. Here, the concept "multi-rotor helicopter" is by no means limited to unmanned aircraft, but also includes manned aircraft, such as E-VTOL aircraft. Typically, such a multi-rotor helicopter includes two or more rotor devices. The rotor device, for example, has a rotor shaft driven by an electric motor, which is more or less vertically oriented in the normal operating position of the multi-rotor helicopter. In addition, a rotor head coupled to the rotor shaft can belong to the rotor device. Typically, the rotor head is arranged on the upper end of the rotor shaft in the normal operating position of the multi-rotor helicopter.

[0007] The rotor device also has at least one rotor blade extending radially outward. The rotor blade is rotatable about a rotor blade axis, whereby the angle of attack of the rotor blade can be changed. The rotor blade axis can be understood as the longitudinal axis of the rotor blade at least in the region in which the rotor blade is fastened ("root"). The rotor blade itself can extend radially outward essentially straight, so that its longitudinal axis is also straight. However, slightly sickle-shaped rotor blades are also known, whose protruding ends are slightly curved.

[0008] In the multi-rotor helicopter according to the invention, the rotor device has a first section, which is driven rotatably around an axis of rotation, and a second section, which is movable relative to the first section around an axis extending parallel to the axis of rotation. Typically, the two sections are arranged coaxially with each other, but other designs are also conceivable. The rotor blade is fastened to the second section, which is movable, that is, twistable relative to the first section at least to a certain extent. The relative position of the second section relative to the first section depends on the torque, with which the first section is driven and set in rotation.

[0009] However, the two sections are not completely independent of one another, since the rotor device has a mechanical coupling that couples the relative position of the first section relative to the second section with the rotational position of the rotor blade about the rotor blade axis. The mechanical coupling thus couples an input parameter (the relative position of the sections) with an output parameter (the rotational position of the rotor blade). That is, as soon as the relative position of one section relative to the other section changes, the rotational position of the rotor blade about the rotor blade axis, i.e. the angle of attack of the rotor blade, also changes.

[0010] If, during operation of the multirotor helicopter, the torque acting on the first section increases - in particular rapidly or even suddenly - this leads, due to the inertia of the second section together with the rotor blade and due to the aerodynamic resistance acting opposite to the direction of rotation, to a forward twisting of the first section relative to the second section in the direction of rotation of the first section, through which the angle of attack of the rotor blade and thus the thrust generated by the rotor device increases. This again increases the aerodynamic drag, so that the increase in rotation speed is kept low or, if necessary, even substantially avoided.

[0011] That is, the adaptive propeller structure according to the invention, which includes flexible elements, achieves an automatic mechanical coupling of the blade angle of attack to the existing engine torque. As a result, the multi-rotor helicopter can be controlled as usual only by the engine power. Of course, when the engine power is increased, a higher thrust is immediately available, because the rotational speed of the propeller does not have to be increased first. This is an advantage in particular for large propellers with a high moment of inertia, which would otherwise require a long time for acceleration.

[0012] In a further embodiment, it is provided that the rotor device has a restoring device, which loads the rotor blade with respect to the rotational position of the rotor blade at least temporarily in the direction of the starting position, in particular has an elastic coupling device, which elastically couples the second section to the first section. In this case, the elastic coupling is arranged in the direction of rotation of the first section or opposite to the direction of rotation of the first section. Thus, the relative twisting of the one section relative to the other section is carried out opposite to the restoring force or opposite to the restoring torque. This further improves the operation of the multi-rotor helicopter according to the invention.

[0013] In a further embodiment, it is provided that the elastic coupling device has at least one elastic bending element, in particular a plurality of elastic bending elements, which are arranged evenly distributed in the circumferential direction of the rotor head, wherein one bending element or a plurality of bending elements are connected to the first section at one end and to the second section at the other end. This is a structurally simple solution. Alternatively, a helical spring arranged coaxially to the axis of rotation may also be provided as a coupling device, or a tubular elastomer body arranged coaxially to the axis of rotation may be included in the coupling device. In addition, it is also conceivable that the bending element extends in the radial direction.

[0014] In a further embodiment, it is provided for this purpose that the elastic coupling device has an at least approximately linear spring characteristic curve, preferably an asymptotic spring characteristic curve. Such a linear spring characteristic curve allows the rotational speed to be kept more or less constant even in the case of a sudden increase in torque. In the case of a correspondingly determined asymptotic characteristic curve, the rotational speed is further improved to an at least approximately constant rotational speed.

[0015] In a further development, it is provided that the rotor device has a first stop which at least indirectly limits the rotational movement of the rotor blade about the rotor blade axis in the direction of a “smaller angle of attack.” This improves the reliability of the multi-rotor helicopter during operation, since a defined minimum angle of attack will not be fallen below in the event of any rotational vibrations between the two sections of the rotor device.

[0016] In a further embodiment, it is provided that the rotor device has a second stop which limits the rotational movement of the rotor blade about the rotor blade axis in the direction of a “larger angle of attack”. This also improves the reliability of the multi-rotor helicopter during operation, since a defined maximum angle of attack is not exceeded in the event of any rotational vibrations that may occur between the two sections of the rotor device and in the event of a strong increase in the torque acting on the first section by the drive. This defined maximum angle of attack is typically an angle of attack at which, at a typical rotational speed of the rotor device, there is no flow separation on the rotor blade.

[0017] This is based on such recognition, that is, especially when the rotation speed of the rotor shaft is accelerated suddenly, the torque can exceed the target torque in the new operating point by several times. In the absence of the stop proposed here, the angle of attack of the rotor blade is also increased to a higher value than in the new operating point, which contains the following danger, that is, the rotor blade enters the flow separation before reaching the new operating point. But at the point of flow separation, the form resistance and therefore the rotor torque also increase by several times. Thereby, the rotor blade will remain in the area of ​​flow separation and produce a new equilibrium state in the state of flow separation. The technical realization of the proposed stop is relatively simple. It may be realized, for example, by a component manufactured in 3D printing.

[0018] In a further development, it is provided that the mechanical coupling has a driver rod which is rigidly connected to the rotor blade (fastened to the second section of the rotor device) and is coupled to the driver section of the first section. This is a particularly simple and realizable embodiment from a technical point of view.

[0019] In a further development, it is provided that the rotational movement of the rotor blade about the rotor blade axis is made possible by a twisted section which is integral with the rotor blade. This is likewise a particularly simple and cost-effective embodiment which can be realized technically. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Next, the embodiment of the present invention will be explained with reference to the accompanying drawings. In the accompanying drawings:

[0021] Figure 1 A schematic top view of a multi-rotor helicopter is shown;

[0022] Figure 2 Show Figure 1 A perspective exploded view of a first embodiment of a rotor device of a multi-rotor helicopter;

[0023] Figure 3 In the first operating state Figure 2 A perspective view of the rotor equipment;

[0024] Figure 4 In the second operating state Figure 2 A perspective view of the rotor equipment;

[0025] Figure 5 A diagram is shown in which the Figure 2-4 The torque of the rotor shaft of the rotor device about the angle of attack of the rotor blades;

[0026] Figure 6 A diagram is shown in which the Figure 2-4 a rotational speed of a rotor shaft of one of the rotor devices relative to the angle of attack of the rotor blades;

[0027] Figure 7a A diagram is shown in which the Figure 2-4 The angle of attack and thrust of the rotor equipment with respect to time;

[0028] Figure 7b A diagram is shown in which the Figure 2-4 The rotational speed of the rotor equipment with respect to time;

[0029] Figure 8 Show Figure 1 A perspective view of a second embodiment of the rotor device of a multi-rotor helicopter;

[0030] Fig. 9 Show Figure 1 A perspective view of a third embodiment of the rotor device of a multi-rotor helicopter;

[0031] Fig.10 Show Fig. 9 A perspective exploded view of the rotor equipment;

[0032] Fig.11 Show Figure 1 A perspective view of a fourth embodiment of the rotor device of a multi-rotor helicopter;

[0033] Fig.12 Show Fig.11 A perspective exploded view of the rotor equipment;

[0034] Fig.13 Show Figure 1 A perspective view of a fifth embodiment of the rotor device of a multi-rotor helicopter;

[0035] Fig.14 Show Fig.13 A side view of the rotor apparatus; and

[0036] Fig.15 Show Fig.13 A top view of the rotor equipment. DETAILED DESCRIPTION

[0037] Functionally equivalent elements and regions in different embodiments and in different figures are then provided with the same reference numerals. They are usually only explained in detail when first mentioned. In addition, for the sake of clarity, not all reference numerals may be recorded in all figures.

[0038] Multirotor helicopters Figure 1 , generally with the reference numeral 10. The multi-rotor helicopter has a basic structure, which comprises, in the present example, four radially outwardly extending arms 12. At the ends of the arms, rotor devices 14 are respectively arranged, comprising a rotation axis or rotor shaft 16 extending perpendicular to the drawing plane, a rotor head 18 coupled to the rotor shaft 16 in the present example, and also two rotor blades 20 fastened to the rotor head 18 in the present example. In principle, multi-rotor helicopters comprising less than or more than four rotor devices are also conceivable. As further stated below, embodiments of the rotor devices are also conceivable that do not have discrete rotor heads. Furthermore, embodiments of the rotor devices are conceivable that have only one rotor blade and a corresponding counterweight, or that have more than two rotor blades. The rotor blades 20 are each rotatable relative to the rotor head 18 about a rotor blade shaft 22. In Figure 1 Rotor blade axes 22 are only plotted for two rotor blades 20 .

[0039] Each rotor device 14 also has an electric drive motor, which is however Figure 1 The electric drive motor is connected to the rotor shaft 16. Figure 1 Multirotor helicopter 10 is assigned a control and regulating device (also not indicated) which can specifically actuate the electric drive motors of rotor device 14 in order to control a multirotor helicopter of known type in this way.

[0040] Reference now Figure 2-4Explanation is given by way of example for a possible first embodiment of a rotor device 14. The rotor device 14 or the rotor head 18 of the rotor device 14 has a first section 24 below and a second section 26 above. The two sections 24 and 26 are currently configured as essentially circular disks by way of example. The first section 24 below has a central and upwardly directed tubular receiving pin 28, into which the second section 26's equally central and downwardly directed journal (not visible) engages. In this way, the second section 26 is rotatably supported on the first section 24 and is rotatably and movably arranged coaxially with respect to the first section. The first section 24 is also fixedly or rigidly connected to the rotor shaft 16, which is only indicated by a dashed line.

[0041] The two rotor blades 20 are fastened to the second section 26 and—as already mentioned above—are fastened rotatably relative to the rotor head 18 about the rotor blade axis 22. For this purpose, the second section 26 has two tubular receiving pins 30 pointing in the radial direction, into which the radially inwardly pointing journals 32 of the rotor blades 20 engage.

[0042] The rotor head 18 also includes two mechanical couplings 34, which are each assigned to a rotor blade 20. Since the two mechanical couplings 34 are designed identically, only one of the two mechanical couplings 34 will be described below.

[0043] In the present case, the mechanical coupling 34 has, by way of example, a driver rod 36 which is rigidly connected to the rotor blade 20. In the present case, the driver rod 36 projects downwardly in the direction of the first section 24, perpendicularly to the rotor blade axis 22, in the region of a root 38 of the rotor blade 20. The mechanical coupling 34 also has a driver section 40 which is coupled to the first section 24.

[0044] The entrainer section 40 is designed in the present case as an example as a receiving opening which opens radially outward and is formed between two rod-shaped projections 42 which extend radially outward from the first section 24. The entrainer rod 36 is received with slight play in the entrainer section 40. As will be described later, the mechanical coupling 34 automatically and mechanically couples the torque-dependent position of the first section 24 relative to the second section 26 to the rotational position of the rotor blade 20 about the rotor blade axis 22 and thus to the angle of attack of the rotor blade 20.

[0045] The rotor device 14 also has an elastic coupling device 44, which elastically couples the second section 26 to the first section 24. In a very schematic and exemplary manner, the elastic coupling device 44 has a helical spring, one end of which is connected to a rod-shaped holding section 46 extending downward from the second section 26, and the other end of which is connected to a rod-shaped holding section 48 extending upward from the first section 24. The elastic coupling device 44 shown in the exemplary embodiment is a tension spring. That is, the two holding sections 46 and 48 are loaded to each other by the elastic coupling device 44.

[0046] The rotor device 14 also has a first stop 50 and a second stop 52. The two stops 50 and 52 are formed in the present case by the axial end regions of a slot 54 extending in the circumferential direction, which is formed in the lower first section 24 and into which the retaining section 46 engages. The relative rotational movement of the second section 26 relative to the first section 24 is therefore limited to the angular range between the first stop 50 and the second stop 52.

[0047] Now especially the reference Figure 3 and 4 The operating principle of the rotor device 14 is explained. Figure 3 Here, rotor device 14 is shown in a first operating state, in which rotor shaft 16 and the two sections 24 and 26 of rotor device 14 together with the rotor shaft are rotated at a constant speed by the above-mentioned electric drive motor. Figure 3 and 4 This is indicated by arrow 56 .

[0048] exist Figure 3 In the first operating state shown in FIG. 4 , the holding section 46 of the second section 26 is pulled by the elastic coupling device 44 toward the first stop 50. In this relative position of the two sections 24 and 26, the driving rod 36 protrudes downwards essentially parallel to the rotor shaft 16. Correspondingly, the angle of attack (not numbered) of the two rotor blades 20 is relatively small. Therefore, the first stop 50 limits the rotational movement of the two rotor blades 20 about the rotor blade shaft 22 in the direction of the “smaller angle of attack”.

[0049] Figure 4 The rotor device 14 is shown in a second operating state immediately after the torque (“drive torque”) acting on the rotor shaft 16 and thus on the first section 24 by the electric drive motor has increased. Due to the increased drive torque, the lower first section 24, which is rigidly coupled to the rotor shaft 16, is rotated in advance relative to the second section 26, as seen in the direction of rotation 56. As a result, the elastic coupling device 44 is stretched and the holding section 46 is moved in the slot 54 toward the second stop 52 corresponding to the position at which the second section 26 is rotated. Figure 4The arrow 57 in FIG.

[0050] By the relative rotation between first section 24 and second section 26, driver lever 36 is driven by driver section 40 (automatic mechanical coupling), whereby the corresponding rotor blade 20 is rotated about rotor blade axis 22 in such a way that the angle of attack of the corresponding rotor blade 20 increases. Thus, second stop 52 limits the rotational movement of the two rotor blades 20 about rotor blade axis 22 in the direction of a “larger angle of attack”. Second stop 52 is selected in this case so that exceeding the maximum aerodynamically suitable angle of attack of rotor blade 20 is prevented.

[0051] The greater angle of attack generates a higher thrust of rotor device 14. In addition, the aerodynamic drag of two rotor blades 20 is increased by the increased angle of attack of two rotor blades 20, whereby a matching torque is applied to rotor shaft 16, which is opposite to the drive torque applied by the electric drive to rotor shaft 16. This has the result that even a sudden increase in the drive torque (if any) only results in a relatively small increase in the rotational speed of rotor shaft 16.

[0052] How the rotational speed and the thrust behave when the drive torque changes depends to a considerable extent on the properties of the elastic coupling device 44. Even when the drive torque changes in abrupt ways, an approximately constant rotational speed over a wide range can be achieved with an elastic coupling device 44 which has an at least approximately linear elastic property, i.e. an at least approximately linear spring characteristic curve. Figure 5 and 6 This is shown in the diagram of FIG. 1 , in which the drive torque M ( M ) on the rotor shaft 16 or the first section 24 is plotted over the angle of attack A of the rotor blade 20. Figure 5 ) or the rotational speed R of the rotor shaft 16 or the first section 24 is recorded with respect to the thrust T ( Figure 6 ). Here, in Figure 5 In , the actual torque is shown as a solid line, whereas the dashed line shows an idealized approximation of the actual torque by a linear spring element. Figure 6 in Figure 1-4 The actual rotational speed in the rotor device 14 is recorded as a solid line and in the case of a conventional propeller as a dotted line.

[0053] If it is desired to maintain a relatively constant rotational speed even with changes in the drive torque, this can be achieved using an elastic coupling device 44 which has a progressive elasticity characteristic, ie a progressive spring characteristic curve. Figure 7a and 7b, in which the angle of attack A and the thrust T are plotted over time t in one diagram and the speed R is plotted over time t in another diagram. At time t1, the drive torque is changed abruptly, in the present example. The solid line corresponds to Figure 1-4 Characteristics of the rotor device 14, the dotted line corresponds to a conventional propeller.

[0054] exist Figure 8 An alternative embodiment of the rotor device 14 is shown in FIG. This embodiment is distinguished from the rotor device 14 by the design of the elastic coupling device 44 in particular. Figure 2-4 Implementation form. The coupling device currently and very exemplarily has a plurality of elastic bending elements 58, which are here again very exemplarily arranged evenly distributed in the circumferential direction of the segments 24 and 26. The bending elements 58 are designed in the form of rectangular, flat and flat bending plates in the unloaded state, for example, formed of GfK or CFK, the longitudinal axis of which extends parallel to the axis of the rotor shaft 16 and the plane of which is oriented radially. Figure 8 The upper end of the curved element 58 is received in the receiving section 60 of the upper second section 26 of the rotor device 14 and fastened there. Figure 8 The lower middle end is received in receiving section 62 of lower first section 24 of rotor device 14 and fastened there.

[0055] When the drive torque acting on rotor shaft 16 and thus on lower first section 24 of rotor device 14 changes, bending element 58 is moved from its position at the lower first section 24, which is ahead in rotational direction 56. Figure 8 The straight, flat shape shown in FIG. 1 is bent into a curved, bent shape.

[0056] exist Fig. 9 and 10 In the embodiment of the present invention, the rotational movement of the rotor blade 20 can be achieved by a twisting section 64 which is integral with the rotor blade 20. The twisting section is elastically twisted when the rotor blade 20 is rotated about the rotor blade axis 22. The twisting section 64 is preferably made of a corresponding plastic material. Due to its elasticity, the connecting section 64 also acts as an elastic coupling device 44 as described above. The two rotor blades 20 are connected to each other. Fig. 9 and 10 In the exemplary embodiment shown in FIG. 1 , it is fastened to the upper second section 26 of the rotor head 18 by means of screws 66 .

[0057] exist Fig.11 and 12In the embodiment of the invention, two star-shaped elastic coupling devices 44 are pushed onto the rotor shaft 16 and rigidly fastened thereto, for example by adhesive bonding. Each of the two elastic coupling devices 44 has a central body 68, which is pushed onto the rotor shaft 16 and adhesively bonded thereto. Four plate-shaped elongated bending elements 58 extend radially outward from the central body 68 in a star shape. The bending elements can be produced, for example, from a thin plastic material, optionally with fiber reinforcement, for example glass fibers or carbon fibers.

[0058] The hollow cylindrical coupling ring 70 is fixedly connectable to a drive motor (not shown), which can be a brushless electric motor, for example, and its rotating section (not shown). The coupling ring has 2x4 receiving sections 62 on its inner side for receiving the protruding ends of the bending elements 58. The bending elements 58 can be glued into the receiving sections 62, for example. In this way, the rotor shaft 16 is connected to the coupling ring 70 in a flexurally elastic manner via the bending elements 58.

[0059] At the rotor shaft 16 Fig.11 and 12 A receiving section 72 is rigidly fastened to the upper middle end, the receiving section having a receiving slot 74 extending transversely to the longitudinal axis of rotor shaft 16. Four elongated, plate-shaped fastening tongues 76 of each of the two rotor blades 20 can engage in the receiving slots. The four fastening tongues 76 are, for example, glued into the receiving slots 74 complementary thereto.

[0060] The fastening tongues 76 extend from the root 38 of the rotor blade 20 at least approximately parallel to the rotor blade axis 22 in such a way that the radially outer narrow sides 77 of the fastening tongues 76 are located on an imaginary surrounding cylindrical wall. Or in other words: the blade planes of two opposite fastening tongues 76 are located in the same plane, whereas the blade planes of two adjacent connecting tongues 76 viewed in the circumferential direction are orthogonal to each other. Of course, in another embodiment, more or less than four fastening tongues can also be present, or a completely different form of torsionally elastic but bending-resistant coupling can be present.

[0061] The fastening tongues 76 are made of a thin plastic material, optionally with fiber reinforcement, for example glass fibers or carbon fibers. The fastening tongues can be very thin, for example in the range of a thickness of only 0.2 mm. By means of the fastening tongues 76, the two rotor blades 20 are connected to the receiving section 72 very rigidly about an axis orthogonal to the rotor blade axis 22, but elastically and torsionally about the rotor blade axis 22, on the other hand. The fastening tongues 76 here form the torsion section 64 already mentioned above.

[0062] A drive rod 36 extends from a root 38 of a rotor blade 20 orthogonally to the rotor blade axis 22 , the protruding end of which is connected, in the present example, to a bending element 78 which extends on the outer side of the coupling ring 70 from a radially protruding fastening section 80 approximately in the circumferential direction of the coupling ring 70 .

[0063] During operation, the coupling ring 70 is set in rotation by the drive engine and, via the elastic coupling device 44, the rotor shaft 16 and the two rotor blades 20 together with the rotor shaft are also set in rotation. If the torque of the drive engine increases, the coupling ring 70 moves ahead of the receiving section 72, as has already been explained above in connection with other embodiments. In this case, the bending elements 58 are bent in the same direction.

[0064] By changing the relative position between coupling ring 70 on the one hand and receiving section 72 on the other hand and by mechanical coupling 34 of rotor blade 20 to coupling ring 70 via drive rod 36, both rotor blades 20 are twisted about rotor blade axis 22 in the direction of a larger angle of attack. In this case, coupling ring 70 forms the above-mentioned "first section 24" and receiving section 72 forms the above-mentioned "second section 26".

[0065] In the rotor equipment 14 Figure 13-15 In the embodiment shown in FIG. 1 , the rotor shaft 16 is fastened with a flat fastening flange 70, which in turn can be connected to a rotating section of a drive engine (not shown). Figure 11-12 In the embodiment of the present invention, two rotor blades 20 are connected to the receiving section 72 via fastening tongues 76. In a particularly preferred embodiment, the fastening flange 70, the rotor blades 20, the fastening tongues 76 and the receiving section 72 / rotor shaft 16 are manufactured as a one-piece part, for example by injection molding or in 3D printing, for example from plastic.

[0066] Figure 13-15 The embodiment of the invention is characterized in that rotor blade shaft 20 is arranged offset upwards by a distance 84 in a direction parallel to rotor shaft 16 relative to a center axis 82 of the unit formed by the four fastening tongues 76. In the upper end face of rotor shaft 16 in the figure, two recesses 54 are provided slightly laterally offset from one another, into which pins 46 extending parallel to rotor blade shaft 22 from root 38 toward rotor shaft 16 engage.

[0067] The fastening flange 70 is again set in rotation by a drive motor (not shown), and the two rotor blades 20 are set in rotation by means of the fastening flange via the rotor shaft 16. When the torque increases, the rotor blade 22 tilts backwards about the center axis 82 opposite to the direction of rotation 56 due to the distance 84, and more precisely due to inertia and air resistance, thereby resulting in an increase in the angle of attack. This rotation is again made possible by the elastic fastening tongues 76, which also generate the necessary restoring force opposite to the tilting direction of the rotor blade 20.

[0068] Here, the fastening tongue 76 also forms the already mentioned twisting section 64, into which the elastic coupling device 44 is integrated. The whole formed by the fastening flange 70 and the rotor shaft 16 forms the above-mentioned first rotatably driven section 24, whereas the two rotor blades 20 form the above-mentioned second section 26 or are comprised of this second section, which is movable relative to the first section 24 about an axis extending parallel to the axis of rotation or axis of rotation 16 based on a tilting movement.

[0069] In the present case, the mechanical coupling 34 which couples the relative position of the first section 24 with respect to the second section 26 to the rotational position of the rotor blade 20 about the rotor blade axis 22 is realized by the distance 84 between the two axes 22 and 82 .

[0070] With its lateral ends, recess 54 forms a first and a second stop 50 and 52 , which define a maximum and a minimum inclination angle and thus a maximum and a minimum angle of attack of rotor blade 20 .

Claims

1. A multi-rotor helicopter (10) having a plurality of rotor devices (14), wherein: The rotor device (14) comprises at least one rotor blade (20), which can rotate around a rotor blade axis (22), and is characterized in that the rotor device (14) comprises: a first section (24) drivable so as to rotate about an axis of rotation (16); a second section (26) which is movable relative to the first section (24) about an axis extending parallel to the rotation axis (16) and to which the rotor blade (20) is fastened or which comprises the rotor blade (20), wherein the relative position of the second section (26) relative to the first section (24) depends on a torque (M) with which the first section (24) is driven; and A mechanical coupling (34) couples the relative position of the first section (24) with respect to the second section (26) to the rotational position of the rotor blade (20) about the rotor blade axis (22).

2. The multi-rotor helicopter (10) according to claim 1, characterized in that: The rotor device (14) has a return device (44) which at least temporarily loads the rotor blade (20) with respect to its rotational position in the direction of a starting position, in particular the rotor device (14) has an elastic coupling device (44) which elastically and at least indirectly couples the second section (26) to the first section (24).

3. The multi-rotor helicopter (10) according to claim 2, characterized in that: The elastic coupling device (44) has at least one elastic bending element (58), in particular a plurality of elastic bending elements (58), which are preferably arranged uniformly distributed along the circumferential direction of the first section (24), wherein the bending elements (58) are connected to the first section (24) at one end and to the second section (26) at the other end.

4. The multi-rotor helicopter (10) according to at least one of claims 2 or 3, characterized in that: The elastic coupling device (44) has an at least approximately linear spring characteristic, preferably an asymptotic spring characteristic.

5. The multi-rotor helicopter (10) according to any one of the preceding claims, characterized in that The rotor device (14) has a first stop (50), which at least indirectly limits the rotational movement of the rotor blade (20) around the rotor blade axis (22) in the direction of a "smaller angle of attack".

6. The multi-rotor helicopter (10) according to at least one of the preceding claims, characterized in that The rotor device (14) has a second stop (52) which at least indirectly limits the rotational movement of the rotor blade (20) around the rotor blade axis (22) in the direction of a "larger angle of attack".

7. The multi-rotor helicopter (10) according to at least one of the preceding claims, characterized in that The mechanical coupling (34) has a driver rod (36) which is rigidly connected to the rotor blade (20) and is coupled to a driver section (40) of the first section (24).

8. The multi-rotor helicopter (10) according to at least one of the preceding claims, characterized in that A rotational movement of the rotor blade (20) about the rotor blade axis (22) is enabled by a twisted section (64) which is integral with the rotor blade (20).

9. A rotor device (14) for a multi-rotor helicopter (10), comprising at least one rotor blade (20) which is rotatable about a rotor blade axis (22), characterized in that: The rotor device has: a first section (24) drivable to rotate about an axis of rotation (116); a second section (26) which is movable relative to the first section (24) about an axis extending parallel to the axis of rotation (16) and to which the rotor blade (20) is fastened, wherein the relative position of the second section (26) relative to the first section (24) depends on a torque (M) with which the first section (24) is driven, and A mechanical coupling (34) couples the relative position of the first section (24) with respect to the second section (26) to the rotational position of the rotor blade (20) about the rotor blade axis (22).

Images